<html>
<head>
<meta content="text/html; charset=windows-1252"
http-equiv="Content-Type">
</head>
<body bgcolor="#FFFFFF" text="#000000">
<br>
<br>
<div class="moz-cite-prefix">On 05/06/2015 07:56 PM, Tangwei (Euler
Architecture & Design Dept) wrote:<br>
</div>
<blockquote
cite="mid:C8D1E566CC4CA845813731FB6FD5C5300108B897@SZXEMI503-MBX.china.huawei.com"
type="cite">
<meta http-equiv="Content-Type" content="text/html;
charset=windows-1252">
<meta name="Generator" content="Microsoft Word 12 (filtered
medium)">
<style><!--
/* Font Definitions */
@font-face
{font-family:SimSun;
panose-1:2 1 6 0 3 1 1 1 1 1;}
@font-face
{font-family:"Cambria Math";
panose-1:2 4 5 3 5 4 6 3 2 4;}
@font-face
{font-family:Calibri;
panose-1:2 15 5 2 2 2 4 3 2 4;}
@font-face
{font-family:SimSun;
panose-1:2 1 6 0 3 1 1 1 1 1;}
@font-face
{font-family:Tahoma;
panose-1:2 11 6 4 3 5 4 4 2 4;}
/* Style Definitions */
p.MsoNormal, li.MsoNormal, div.MsoNormal
{margin:0cm;
margin-bottom:.0001pt;
text-align:justify;
text-justify:inter-ideograph;
font-size:10.5pt;
font-family:"Calibri","sans-serif";
color:black;}
a:link, span.MsoHyperlink
{mso-style-priority:99;
color:blue;
text-decoration:underline;}
a:visited, span.MsoHyperlinkFollowed
{mso-style-priority:99;
color:purple;
text-decoration:underline;}
span.EmailStyle17
{mso-style-type:personal;
font-family:"Calibri","sans-serif";
color:windowtext;}
span.EmailStyle18
{mso-style-type:personal-reply;
font-family:"Calibri","sans-serif";
color:#1F497D;}
.MsoChpDefault
{mso-style-type:export-only;
font-size:10.0pt;}
@page WordSection1
{size:612.0pt 792.0pt;
margin:72.0pt 90.0pt 72.0pt 90.0pt;}
div.WordSection1
{page:WordSection1;}
--></style><!--[if gte mso 9]><xml>
<o:shapedefaults v:ext="edit" spidmax="1026" />
</xml><![endif]--><!--[if gte mso 9]><xml>
<o:shapelayout v:ext="edit">
<o:idmap v:ext="edit" data="1" />
</o:shapelayout></xml><![endif]-->
<div class="WordSection1">
<p class="MsoNormal"><span style="color:#1F497D" lang="EN-US">Would
you help to list the object copying policy for different
GC? Or pointing out where to find such information?
</span></p>
</div>
</blockquote>
<br>
For the most part UseParallelGC and UseG1GC has depth-first
copying. UseConcMarkSweepGC <br>
and UseSerialGC use breadth-first. I qualify that because I've
heard people argue about whether<br>
that's 100% true.<br>
<br>
Jon<br>
<br>
<blockquote
cite="mid:C8D1E566CC4CA845813731FB6FD5C5300108B897@SZXEMI503-MBX.china.huawei.com"
type="cite">
<div class="WordSection1">
<p class="MsoNormal"><span style="color:#1F497D" lang="EN-US"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D" lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D" lang="EN-US">Regards!<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D" lang="EN-US">wei<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D" lang="EN-US"><o:p> </o:p></span></p>
<div>
<div style="border:none;border-top:solid #B5C4DF
1.0pt;padding:3.0pt 0cm 0cm 0cm">
<p class="MsoNormal" style="text-align:left" align="left"><b><span
style="font-size:10.0pt;font-family:"Tahoma","sans-serif";color:windowtext"
lang="EN-US">From:</span></b><span
style="font-size:10.0pt;font-family:"Tahoma","sans-serif";color:windowtext"
lang="EN-US"> hotspot-gc-dev
[<a class="moz-txt-link-freetext" href="mailto:hotspot-gc-dev-bounces@openjdk.java.net">mailto:hotspot-gc-dev-bounces@openjdk.java.net</a>] <b>On
Behalf Of </b>
Jon Masamitsu<br>
<b>Sent:</b> Thursday, May 07, 2015 8:23 AM<br>
<b>To:</b> <a class="moz-txt-link-abbreviated" href="mailto:hotspot-gc-dev@openjdk.java.net">hotspot-gc-dev@openjdk.java.net</a><br>
<b>Subject:</b> Re: Depth first object copying for all
GC?<o:p></o:p></span></p>
</div>
</div>
<p class="MsoNormal" style="text-align:left" align="left"><span
lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal" style="margin-bottom:12.0pt"><span
lang="EN-US"><o:p> </o:p></span></p>
<div>
<p class="MsoNormal"><span lang="EN-US">On 5/6/2015 4:34 AM,
Tangwei (Euler Architecture & Design Dept) wrote:<o:p></o:p></span></p>
</div>
<blockquote style="margin-top:5.0pt;margin-bottom:5.0pt">
<p class="MsoNormal"><span lang="EN-US">Hi All, <o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"> As a newbie in GC, I
found some discussion on object copying order in following
slides: breadth vs. depth.
<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">It mentioned that <i>“Any
static policy will hurt some applications and help
others”.
</i>After searching, there is a BZ shows <o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">the object copying
order has been switched from breadth to depth for
ParallelGC in OpenJDK, please correct if I am wrong.
<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">Anyone can help to
confirm if all GC in OpenJDK use depth first copying now?
<o:p></o:p></span></p>
</blockquote>
<p class="MsoNormal" style="text-align:left" align="left"><span
style="font-size:12.0pt;font-family:"Times New
Roman","serif"" lang="EN-US"><br>
No, not all the GC's use depth first copying.<br>
<br>
<br>
<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">Is there any performance
consideration to choose depth first instead of controlling
by option?<o:p></o:p></span></p>
<p class="MsoNormal" style="text-align:left" align="left"><span
style="font-size:12.0pt;font-family:"Times New
Roman","serif"" lang="EN-US"><br>
Yes, there is a performance cost to optionally using
depth-first or breadth-first.<br>
ParallelGC used to have such an option. It made the code
harder to maintain and,<br>
as far as I can recall, there was very little use of the
option. We removed the<br>
it. I recall maybe 1 complaint about it.<br>
<br>
Jon<br>
<br>
<br>
<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"> <o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><a
moz-do-not-send="true"
href="http://www.oracle.com/technetwork/server-storage/ts-6434-159339.pdf">http://www.oracle.com/technetwork/server-storage/ts-6434-159339.pdf</a><o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"> <o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-family:"Arial","sans-serif""
lang="EN-US"> </span><span lang="EN-US"><o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-family:"Arial","sans-serif""
lang="EN-US"><a moz-do-not-send="true"
href="https://bugs.openjdk.java.net/browse/JDK-6450584">https://bugs.openjdk.java.net/browse/JDK-6450584</a>:
Improve object copying order in parallel scavenge</span><span
lang="EN-US"><o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"> <o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"> <o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">Regards!<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">wei <o:p></o:p></span></p>
<p class="MsoNormal" style="text-align:left" align="left"><span
style="font-size:12.0pt;font-family:"Times New
Roman","serif"" lang="EN-US"><o:p> </o:p></span></p>
</div>
</blockquote>
<br>
</body>
</html>